Heat recovery ventilation (HRV), also known as mechanical ventilation heat recovery (MVHR), is an energy recovery ventilation system that works between two sources at different temperatures. … A typical heat recovery system in buildings consists of a core unit, channels for fresh air and exhaust air, and blower fans.
Building exhaust air is used as either a heat source or heat sink depending on the climate conditions, time of year, and requirements of the building. Heat recovery systems typically recover about 60–95% of the heat in exhaust air and have significantly improved the energy efficiency of buildings.
A heat recovery system is designed to supply conditioned air to the occupied space to continue the desired level of comfort. The heat recovery system keeps the house fully ventilated by recovering the heat which is coming from the inside environment. Heat recovery systems basically work by transferring the thermal energy (enthalpy) from one fluid to another fluid, from one fluid to a solid or from a solid surface to a fluid, at different temperatures and in thermal contact. Additionally, there is no direct interaction between fluid and fluid or fluid and solid in most of the heat recovery systems. In some application of heat recovery systems, fluid leakage is observed due to pressure differences which can cause mixture of the two fluids.